FWIW we already do both chemo and radiation treatments for cancer that kill good cells as well the bad ones.
Question is, will it work, or is it likely to work?
Breaking proteins up would be really hard to direct at only venom proteins. A lot of good ones could also break.
Cells are different enough to behave differently, so they can target cancer cells selectively. Almost like cells = buildings and proteins = bricks.
Hitting a pile of bricks covered by tarp with a huge hammer and only breaking one of the bricks would be very hard to do consistently. Similar in the body.
I also think that something like a tazer if used wrong or too much could hurt muscles enough to make muscle chemicals go into the blood to the kidneys and cause kidney failure. That is called rhabdomyolysis. It also can happen from the snake venom so even more risk is not good.
Hope your week is good!